Name:	exr_NoncontrollingInterestConversionOfPreferredOperatingPartnershipUnitsBeforeMaturityOfLoanMaximum
Namespace Prefix:	exr_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Noncontrolling Interest, Conversion Of Preferred Units to Common Units, Number Of Units Issued

No definition available.

Name:	exr_NoncontrollingInterestConversionOfPreferredUnitstoCommonUnitsNumberOfUnitsIssued
Namespace Prefix:	exr_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Represents the annual rate of return of preferred operating partnership units.

No definition available.

Name:	exr_NoncontrollingInterestInPreferredOperatingPartnershipUnitsAnnualRateOfReturn
Namespace Prefix:	exr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the ratio for conversion of preferred operating partnership units into common OP units.

No definition available.

Name:	exr_NoncontrollingInterestInPreferredOperatingPartnershipUnitsConversionRatio
Namespace Prefix:	exr_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

Represents the fixed liquidation value of preferred operating partnership units.

No definition available.

Name:	exr_NoncontrollingInterestInPreferredOperatingPartnershipUnitsFixedLiquidationValue
Namespace Prefix:	exr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Represents the carrying amount of preferred operating partnership units attributable to noncontrolling preferred unit holders on which the fixed priority return is granted.

No definition available.

Name:	exr_NoncontrollingInterestInPreferredOperatingPartnershipUnitsFixedPriorityReturnAmount
Namespace Prefix:	exr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Represents the liquidation value of preferred operating partnership units attributable to noncontrolling preferred unit holders on which the fixed priority return is granted.

No definition available.

Name:	exr_NoncontrollingInterestInPreferredOperatingPartnershipUnitsFixedPriorityReturnRedemptionValue
Namespace Prefix:	exr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Represents the fixed priority return, as a percent, of preferred operating partnership units attributable to noncontrolling preferred unit holders on which the fixed priority return is granted.

No definition available.

Name:	exr_NoncontrollingInterestInPreferredOperatingPartnershipUnitsFixedPriorityReturnStatedRateOfReturn
Namespace Prefix:	exr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the liquidation value per unit of preferred operating partnership units.

No definition available.

Name:	exr_NoncontrollingInterestInPreferredOperatingPartnershipUnitsLiquidationValuePerUnit
Namespace Prefix:	exr_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

Represents the period from the date of issuance after which preferred units will become redeemable at the option of the holder.

No definition available.

Name:	exr_NoncontrollingInterestInPreferredOperatingPartnershipUnitsPeriodFromDateOfIssuanceAfterWhichUnitsBecomeRedeemable
Namespace Prefix:	exr_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Note Receivable, Reduction Of Noncontrolling Interests

No definition available.

Name:	exr_NoteReceivableReductionOfNoncontrollingInterests
Namespace Prefix:	exr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Represents the stated interest rate of notes receivable.

No definition available.

Name:	exr_NotesReceivableStatedInterestRate
Namespace Prefix:	exr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Real Estate Property Asset Acquisition, Consideration Transferred, Equity Interest Issued Or Issuable

No definition available.

Name:	exr_RealEstatePropertyAssetAcquisitionConsiderationTransferredEquityInterestIssuedOrIssuable
Namespace Prefix:	exr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The number of shares converted in a noncash (or part noncash) transaction. Noncash is defined as transactions during a period that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4313-108586

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4332-108586

Name:	us-gaap_ConversionOfStockSharesConverted1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Aggregate amount of receivables to be collected from related parties where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth, at the financial statement date. which are usually due after one year (or one business cycle).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.11)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(k)(1))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Name:	us-gaap_DueFromRelatedPartiesNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_MinorityInterestLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The number of shares issued as [noncash or part noncash] consideration for a business or asset acquired. Noncash is defined as transactions during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4332-108586

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4313-108586

Name:	us-gaap_NoncashOrPartNoncashAcquisitionNoncashFinancialOrEquityInstrumentConsiderationSharesIssued1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

The cash outflow for a loan, supported by a promissory note, granted to related parties where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3213-108585

Name:	us-gaap_OriginationOfNotesReceivableFromRelatedParties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The number of preferred units outstanding.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70434-108055

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
-Subparagraph (SAB Topic 4.F)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187171-122770

Name:	us-gaap_PreferredUnitsOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Name:	us-gaap_PreferredUnitsByNameAxis=exr_SeriesAUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PreferredUnitsByNameAxis=exr_SeriesBUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PreferredUnitsByNameAxis=exr_SeriesCUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PreferredUnitsByNameAxis=exr_SeriesDUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	dei_LegalEntityAxis=exr_HoldersOfSeriesAPreferredOperatingPartnershipUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: